Hydrofoils have been used on different watercraft for nearly 100 years. They have been used on engine driven watercraft both large and small, sailboats, human powered boats, windsurfers, wakeboards, and our favorite waterski(s).
The first hydrofoil boat dates back to 1906 designed and built by the Italian Inventor, Enrico Forlanini (1948-1930). The foil design was made from the classic “Ladder” type construction which has muliple struts coming down with multiple wings between them. It had a 60 hp engine driving two counter-rotating air props and during testing in 1906, the craft reached a top speed of 42.5 mph.
Alexander Graham Bell and Casey Baldwin developed a boat based on Floranini’s Ladder style foil in 1919. Bell was the primary designer and Baldwin built the boat based on their designs. The boat was called the Hydrodrome 4 (HD-4) and set the record for the fastest hydrofoil boat speed at 60 knots which stood until the 1960’s.
In the 1960’s, many countries developed their own version of a hydrofoil ship for their militaries. The US Navy and Boeing developed the first Jetfoil, the Patrol Hydrofoil Missileship (PHM), which was the predecessor to the Jetski. They also developed a commercial passenger version.
The Boeing PHM
The Boeing Jetfoil
In the early 1960’s, the first “waterski” hydrofoil was developed by Walter Woodward, an aeronautical engineer from Upper Newton Falls, Massachusetts. The first person to test and fly Woodward’s invention was Frazer Sinclair. This was the beginning of towed hydrofoiling!
Woodward partnered with Lucas Emmanuell, a Harvard Business graduate, and patented the hydrofoil waterskis. They established Cosmo Dynamics that would market their product as the Dynaflite Hydrofoil. The Hydrofoil consisted of two regular waterskis with two struts attached to each ski with a bi-wing design. They would go on to develop other hydrofoil products such as a Dynaboard and a hydrofoil catamaran.
Highlights of the Dynaflite Hydrofoil include the first public demostration at Cypress Gardens by Buster MacCalla (advertised Dynaflite hydrofoils on the brochure cover) and continued appearances by “Banana” George Blair. He would dress up in a yellow Santa Claus suit and parade around Lake Eloise on the hydrofoil skis wowing the crowd at Cypress Gardens during the Christmas Show.
Banana George on Hydrofoil waterskis
After 20 years and changing from Cosmo Dynamics to Custom Dynamics the Dynaflite Hydrofoil vanished as a marketable product.
So how did the hydrofoils popularity come back? Mike Murphy’s water ski pro shop on the Colorado became the place where the Dynaflite Hydrofoil was put to the test in the late 1970’s. As a hot dog enthusiast Murphy began testing the Hydrofoil’s capabilities and limitations by skiing them in a slalom course and attempting to jump out of the water. Eventually the foil materials on the Dynaflite Hydrofoil were stressed beyond their design limits and they began to break.
Dynaflite Hydrofoiling on the Colorado River
Henry “Buck” Buxton with aid from Mike Murphy, took Emmanuell’s design when the patents were up and strengthened the foil assembly and increased performance by improving the foil profile for less drag.
Mike Murphy jumping
Mike Murphy and Bud Holst in 1972 developed the kneeboard for water-skiing. The biggest problem with the kneeboard is that it took away the shock absorbing effect of your knees. Mike accidentally came up with the idea that if he took the hydrofoil and put it on a knee board, it would solve the problem of kneeboards with a smoother ride and the biggest problem of stand-up skis being too sensitive to forward and backward motion by lowering the center of gravity.
Mike Murphy and Bob Woolley designed a new prototype by taking the foil assembly based on Emmanuell’s design and attaching it to a kneeboard. They changed the design by replacing the bi-wing design with a the single wing foil. Mike Mack and Buck Buxton were instrumental in providing input and improving the design by testing.
The double strut on the kneeboard was not necessary for strength (more convenient from previous prototypes), so a single strut/single wing was developed for the kneeboard. This prototype was sold to Hydroslide, a major kneeboard manufacturer, but it never took off. Upon signing the contract with Hydroslide, both Bob and Mike were forbidden to ride the Hydrofoil kneeboard for 5 years because this was now proprietary to Hydroslide and word could not get out about it. They could still ride Stand-up hydrofoil waterskis. There was a major draw back to the hydrofoil kneeboard, in that it was very hard on your ankles after long rides. Since the rope tension was a lot less than riding an ordinary kneeboard riding a longer time was much easier.
From all the prototype riding Bob had been doing he was starting to have nerve damage to his ankles. The thought came to Bob that if there was a seat to sit on with foot bindings, maximum comfort could be achieved without damage to your legs and a lower center of gravity. Bob Woolley applied the concept of the “Sit Ski” and developed a hydrofoil with a seat and two skis. It used the double strut design with skis that were stationary versus the articulated Skis on the “Sit Ski”. The first sit down hydrofoil was ridden in 1984 by Bob and was the major turning point for the modern day hydrofoils.
Sit Ski rider – Mike Mack
First sit-down hydrofoil
After getting blasted with water from the center of the skis, Mike came up with the idea to have Bob move the skis together so that the wash from the spray would be off to the sides of the ski. In addition, they changed the hydrofoil from a double strut to a single strut. This design eventually became a single ski with a single strut.
Mike and Bob were hydrofoiling on the river, Bob with his new seated hydrofoil and Mike with his stand-up two ski hydrofoil. When Mike would fall on either the stand-up and seated hydrofoils he would get hit by the foil and he decided that he would not ride a hydrofoil until they added a seat belt to it. At about this time Mike Mack was developing the “Mackstrap”, a heel strap used on a hot dog slalom ski that did not make it to the market. This strap was used on the hydrofoil prototype to help keep the rider’s feet from coming out. These two additions were the final necessary steps in making the sit-down hydrofoil safe for riders.
At this point, Air Chair was formed to put hydrofoils into production with the first one sold in January 1990. With Bob Woolley and Mike Murphy’s name on the patent, they started a corporation called RBM (Robert, Brad, and Mike) to manufacture the Air Chair. Bob’s role was developing and running Air Chair, Mike’s role was to travel and promote Air Chair. The foils were made of cast aluminum and powder coated. The boards were fiberglass with foam core pressed at the HO factory by Jake Kinnison. Riders began to modify these early foils by stripping the powder coating off, filing the edges and polishing the foil to improve performance. Winglets were added to the front wing to provide for more lift. Thin pads were added to the seats to maximize friction so the rider would not slip as easily. Double locking Velcro seat belts were used to “cinch” down the rider into the seat. The foils would move back and forth in the seat tower because it was bolted from the top of the foil, so many riders would thru-bolt the foil into the seat tower. Shims were added to modify the lift. Many of these improvements would be incorporated into future foil designs from the factory.
After several years of working together, Mike Murphy, Brad Barnett, and Bob Woolley decided they could no longer work together. Bob continued to run Air Chair, Mike Murphy formed Sky Ski, and Brad pursued other opportunities.
Air Chair developed a new hydrofoil with an aluminum seat tower and a new curved blade system. Not only to improve performance but to provide softer landings as well. A flat rear blade is included for beginners providing for a stable ride for learning. These aluminum parts are cast in a hard tool. The new production technique delivers the highest strength aluminum. Also allowing the complete unit to be the lightest and strongest hydrofoil waterski. A tapered foil system was also incorporated into the Air Chair to eliminate movement in the seat. Streamling the foil assembly for better performance without compromising quality or strength.
Stealth Air Chair
Sky Ski developed a hydrofoil with a different fuselage design. A keel was added to the bottom to provide for more strength and enabling a thinner fuselage. The Pro model foil is made from cast aluminum in a hard tool. The Pro model comes with two options for the seat tower, a tower made from aluminum plate and a tower with a shock. The Shock Tower was developed by Bobby Taylor and Jon Wilborn at Mike Murphy’s request in an effort to minimize the impact of landing on the riders back. The Limited Edition Sky Ski comes with a carbon fiber board, a foil made from the highest strength aluminum, and a specially made machined aluminum shock tower that is lighter than the Pro model. Since the foil material is much stronger, the profile is much thinner, which provides for reduced drag and better performance.
Limited Edition Sky Ski
Pro Shock Tower Sky Ski
There is a hydrofoil designed for surfing which is a smaller than average surfboard with snowboard boots attached to it and this hydrofoil is used to ride the ocean waves for miles. The surfing foil is offered under license to other surfing manufacturers/distributors by both Air Chair and Sky Ski.
There is a sit down/stand-up hydrofoil combination that is convertible from one configuration to another. This hydrofoil is offered by Sky Ski.
Hang onto a Kite with one of these hydrofoil boards and you have kite Foilboarding.
There is a windsurfer shaped by Carl Hill glassed by Tominator and designed by Rush Randall on Maui.
Another hydrofoil-based paipo board was developed in the San Diego area. In contrast to the primary design objectives of other hydrofoil surf craft, this design was to enhance maneuverability (vs. speed and smooth ride). An early prototype is shown below. It differs from other existing wave-propelled hydrofoil-based surf craft in that it relieves the rider from maintaining the “flight height”.
It is a great time for all of us foilers. Keep on innovating……..